1. Field of the Invention
This invention is directed to a filter structure for cameras where the filter case is removably attached to the camera case, and two polarized filters are rotated together.
2. Description of the Prior Art
The majority of inexpensive cameras are in that class known as "viewfinder cameras." The viewfinder through which the photographer sees the scene toward which his lens is directed is separate from the lens. This simplifies the viewfinder optics, but presents other problems. For example, setting the proper focal position of the lens must be accomplished by using estimated distance to the object, by using an optical range finder, or, in the most inexpensive cameras, by using a lens of sufficiently small aperture that it has a depth of focus over a useful range without focusing.
When a lens filter is desired, the effect of colored filters on black and white film can be readily assessed from previous experience, and there is no need to see through the colored filter. In fact, viewing through a colored filter presents information to the eye which does not correspond to the manner in which that filter acts with respect to the sensitivity spectrum of black and white film; however, when considering color film, the only useful filter is the polarized filter. It is employed to reduce glare and soften bright reflections. As contrasted to the color filter, the scene must be observed through the polarized filter because the polarized filter must be angularly set to achieve the desired glare reduction. Thus, the same filter angle must be achieved over both the viewfinder and the lens. Such structure has not been available for inexpensive cameras where the flter case attaches to the camera body and can be readily installed and removed by the photographer.